Crop dusting, or aerial top dressing, involves spraying crops with fertilizers, pesticides, and fungicides from an agricultural aircraft. Agricultural aircraft are often purpose built, and include fixed wing airplanes and helicopters. In most cases, the fertilizers, pesticides, and fungicides are applied in liquid form from a spraying apparatus affixed to the crop dusting aircraft. The spraying apparatus includes wet tanks which store the applied liquids, pressurization apparatus to transfer the applied liquids from the wet tanks to a spray boom, and spray nozzles arranged approximately symmetrically along the spray boom and oriented in a downward direction. Controls are provided near the pilot to control the release of the applied liquids to a selected target area. In most cases, the selected target area is a concentration of several acres of plants or trees such as an orchard or plowed field.
In order to control populations of harmful insects to crops, it is sometimes useful to release beneficial insects in close proximity to the crops being protected. Beneficial insects may be bred to attack and reduce populations of harmful insects, without harming crops.